In order to manufacture an integrated circuit device in which a large number of semiconductor elements such as a transistor are provided, techniques for shrinking patterns are indispensable for improvement of integration. Recently, in order to further shrink patterns, various lithography techniques have been developed actively. One of such lithography techniques is an exposure technique using EUV light as exposure light. The wavelength of the EUV light used as exposure light is as extremely short as approximately 13.5 nm. Thus, the EUV lithography technique is considered as a lithography technique that resolves extremely fine patterns having the size of 50 nm or less.
Since a material that transmits the EUV light having such a wavelength is difficult to obtain, an exposure optical system of an EUV exposing apparatus is not a transmissive optical system but a reflective optical system. Also, an EUV mask for EUV exposure is not a transmissive mask but a reflective mask. The EUV mask is manufactured by forming a mask pattern on a blank. The mask pattern is formed selectively an absorption film which absorbs EUV light. The blank has a reflection film for EUV light made of a multilayer film provided on a substrate.
In this type of the EUV lithography technique, the blank for EUV mask itself is a structural body having a fine structure and moreover, the wavelength of the EUV light is extremely short, and thus, a defect caused by the blank might appear in an exposed image. Therefore, in order to improve yield of the EUV lithography, it is preferable that a blank is inspected before a mask pattern is formed so that only a blank without a defect is used. However, since it is difficult to completely eliminate a defect in the blank, if only blanks without a defect are to be used, the yield of the blank is lowered, and a manufacturing cost of the EUV mask is increased, which is a problem.